LONDON. Royal Society, May 13.—Prof. C. S. Sherrington, president, in the chair.—G. W. Walker: The problem of finite focal depth revealed by seismometers. Observations of the emergence angle of P waves at Pulkovo suggest that the depth of focus is of order one-fifth of the earth's radius. Important modifications are necessary in the interpretation of seismo-grams and in the attempt to determine how speed of propagation depends on depth. A test of the accuracy of the Pulkovo values can be made by a scrutiny of seismograms for distances >11,000 kilometres. Corresponding measures of the angle of emergence of S waves by means of three component seismometers are required.—E. A. Griffiths: A liquid oxygen vaporiser. The liquid oxygen is contained in a metal vacuum vessel. The emission of gas is governed by bringing a flexible portion of the outer wall into contact with the inner; the degree of contact determines the rate of transmission of heat. An desired rate of gas evolution can be obtained up to 10 litres per minute, and the delivery remains constant.—Dorothy M. Palmer and W. G. Palmer: Some experiments on the catalytic reduction of ethylene to ethane. The hydrogenation of ethylene in the presence of nickel has been quantitatively examined. The mixture of ethylene and hydrogen was brought into contact with nickel in motion in an electrically heated tube. The rate of hydrogenation was measured by the rate at which a mixture of ethylene and hydrogen in equal proportions by volume had to be passed into the tube to maintain the gas therein at constant pressure. The effects of varying conditions were studied. The curves showing rate of reaction against time display “induction” periods during which no hydrogenation took place, varying in duration from a few seconds to many hours, according to the conditions of the experiment. Then the rate of reaction increases rapidly to a sharp maximum, and decreases less rapidly to a lower value, which decreases slowly. A theory is advanced to account for these effects.—W. G. Palmer: The catalytic activity of copper. Part ii. The activity of copper when prepared from oxide by reduction with carbon monoxide and methyl alcohol vapour is discussed. Constant-boiling mixtures of several alcohols with water were used as reacltants. Water acts as a positive, and hydrogen as a negative, auxiliary catalyst when adsorbed on the copper. The activity-temperature curves for a catalyst prepared by carbon monoxide obey a simple exponential law. Between 270° and 280° C. the activity curves generally undergo a sudden change of direction corresponding to a great reduction of the temperature coefficient. This is attributed to the diminution in the thickness of the adsorbed alcohol layer to at most two molecular diameters. The activity of the catalyst does not increase continuously, as the temperature of its preparation from oxide is lowered.—Prof. C. F. Jenkin and D. N. Shorthose: The total heat of liquid carbonic acid. The total heat of carbonic acid between temperatures of +10° C. and +100° C. and between pressures of 900 Ib, and 1800 Ib. per square inch was measured. The values hitherto accepted, based on the assumption that the specific heat at constant volume does not change over this range, require slight correction.—Dr. A. O. Rankine: The viscosity and molecular dimensions of gaseous cyanogen. The viscosity of gaseous cyanogen has been measured at 15° C. and 100° C., the values obtained being, respectively, 0.986 × 10- 4 and 1.264 × 10- 4 C.G.S. units. Assuming Sutherland's law of temperature variation, the data have been used to calculate Sutherland's constant (C. =280) and the viscosity at 0° C. (η0.–0.935 × 10- 4 C.G.S. units). The mean collision area of the molecule of cyanogen deduced, –1.31 × 10- 15 cm.2, proves to be practically the same as that of a bromine molecule, 1.28 × 10- 15 cm.2 This is consistent with the evidence from crystal examination, for the molecular volumes of KBr and KCN are nearly equal. If X-ray crystal examination should prove that KCN and KBr are strictly isomorphous, the results here obtained are consistent with the Lewis-Langmuir view that the cyanogen molecule has a size and shape nearly the same as those of two nitrogen molecules linked together by sharing one pair of outer electrons.